They play completely diff. roles. McHale did not bring the ball up the court, he did not shoot 3's. He had fantastic pivot moves close to the basket and an incredibly soft touch. And he had/has exceptionally long arms and would block shots while keeping the ball in play instead of knocking it into the stands (just like an offensive rebound for the other team...)

And there is no flippin way Lebron could beat McHale in a post game. McHale would score over him every time he got the ball. And if Lebron tried to post Mchale up... he wouldnt... he would try to go past him. If he did try and post him up, jumping from a post position (ie without a flying start) he would find the ball blocked unless he tried a fall away jumper which he would have to do.
There is a reason Lebron does not cover Duncan down low also. He would foul out and get scored on.

They play completely diff. games in diff. positions.